X0306 4 2022-03-14 0 0001382101 SUTRO BIOPHARMA, INC. STRO 0001309660 NEWELL WILLIAM J C/O SUTRO BIOPHARMA, INC. 111 OYSTER POINT BLVD. SOUTH SAN FRANCISCO CA 94080 1 1 0 0 CEO Common Stock 2022-03-14 4 P 0 10000 7.7508 A 116525 I By William J. Newell Family Trust DTD 03/15/2019 Common Stock 10577 I By Newell Family Revocable Trust DTD 08/14/2008 Common Stock 113460 D The reported price in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $7.68 to $7.85 per share, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon written request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote. The securities are held of record by the reporting person as trustee of the William J. Newell Family Trust DTD 03/15/2019. The securities are held of record by the reporting person as trustee of the Newell Family Revocable Trust DTD 08/14/2008. /s/ Edward C. Albini as attorney-in-fact for William J. Newell 2022-03-15